1. Technical Field
The present invention relates to an eye refractive power measurement apparatus for objectively measuring a refractive power of an examinee's eye.
2. Related Art
There has been known an eye refractive power measurement apparatus that includes a measuring optical system for projecting measurement light onto a fundus of an examinee's eye, extracting as ring-shaped light the measurement light reflected from the fundus, and causing a two-dimensional imaging device to capture a ring-shaped image (refer to JP 2005-185523 A). In this apparatus, a light deflecting member is arranged rotatably on a common optical path of a light projecting optical system for projecting the measurement light and a light receiving optical system for receiving the measurement light. Thus, this apparatus allows measurement of an average refractive power in a pupil of the examinee's eye.
In daily life, a diameter of a pupil of an eye varies when ambient brightness differs at day and night or in an indoor environment and an outdoor environment. For this reason, there is required an objective inspection (measurement) for refractive powers according to different diameters of the pupil.
However, the conventional apparatus merely measures an eye refractive power, based on a fixed diameter (e.g., 4 mm) of the pupil for the following reason. That is, the conventional apparatus is incapable of changing a measurement range for the eye refractive power.